Related Parties - Investments in Unconsolidated Subsidiaries, Equity Securities and Other (Balance Sheet and Earnings Activity) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Net revenues	$ 777	$ 572
Expenses	19	13
Receivables	513		$ 523
Payables	10		20
Megapolis Group
Schedule of Equity Method Investments [Line Items]
Net revenues	496	359
Receivables	271		375
Other
Schedule of Equity Method Investments [Line Items]
Net revenues	281	213
Expenses	19	$ 13
Receivables	242		148
Payables	$ 10		$ 20